Coordinator AP Scheduling for Bounded Latency in EHT OBSS
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Solution Overview
Problem
Current wireless communication standards, such as 802.11, face challenges in providing bounded latency and jitter in managed overlapping basic service sets (OBSS) scenarios due to contention and interference, which are not adequately addressed by existing solutions like EDCA and HCCA, especially for time-sensitive applications.
Innovation Solution
A scheduled access framework is introduced, where a coordinator access point manages channel access across multiple APs, using multi-AP trigger frames and traffic specifications to assign non-overlapping channels, disable contention access, and schedule service periods for time-sensitive traffic, ensuring predictable and reliable channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scheduled access framework with coordinator AP is implemented, then worst-case latency and jitter are bounded, but device complexity and protocol overhead increase
Solution Approach 1:
The patent segments the OBSS into multiple TWT groups, each managed by a coordinator AP. This divides the complex coordination problem into smaller, manageable units where each coordinator handles only its assigned group, reducing individual coordinator complexity while maintaining overall system reliability through structured resource allocation.
Solution Approach 2:
The patent implements preliminary action by establishing TWT service periods and resource allocations in advance before time-sensitive traffic arrives. Coordinators pre-allocate non-overlapping channels and time slots to STAs, ensuring bounded latency without requiring complex real-time arbitration when traffic actually occurs.
2Productivity
If multi-AP trigger frames are used to manage channel access, then channel allocation efficiency improves, but communication overhead increases
Solution Approach 1:
The patent makes trigger frames multi-functional by enabling them to carry both resource allocation information and traffic specification parameters simultaneously. A single trigger frame type can serve multiple purposes: scheduling uplink transmissions, allocating resources, specifying traffic requirements, and coordinating multi-AP operations, thereby reducing the number of separate control messages needed.
Solution Approach 2:
The patent merges previously separate control functions into unified trigger frame structures. Resource allocation fields, TWT parameters, and traffic specifications are combined into single composite frames that accomplish multiple coordination tasks in one transmission, improving efficiency while managing overhead through consolidation.
3Reliability
If contention access is disabled for time-sensitive traffic, then latency bounds are improved, but access flexibility and adaptability decrease
Solution Approach 1:
The patent implements dynamic access modes where STAs can switch between scheduled contention-free access during TWT service periods and contention-based access outside these periods. This dynamic behavior allows the system to provide strict latency bounds when needed while maintaining flexibility and adaptability for other traffic types and scenarios.
Solution Approach 2:
The patent applies different access qualities to different traffic types and time periods. Time-sensitive traffic during TWT service periods receives guaranteed contention-free access with bounded latency, while other traffic can utilize flexible contention-based access. This local differentiation maintains latency bounds for critical traffic without sacrificing overall system adaptability.
Data Source
AI summary
An access point (AP) may be configured by processing circuitry to operate as a coordinator AP for performing BSS channel level coordination. The coordinator AP is configured to assign non-overlapping channels to one or more coordinated APs of overlapping BSSs to schedule time-sensitive traffic to help ensure bounded latency, jitter and reliability per BSS. In some embodiments, the AP may be configured for performing transmission level coordination and may initiate a coordinated transmission opportunity (TXOP) for resource assignment to control contention access among managed BSSs. To perform the BSS channel level coordination, the coordinator AP is configured to encode a multi-AP trigger frame (M-TF) to initiate the coordinated TXOP. The M-TF may be encoded to include a time-sensitive operation IE indicating how each STA is to access the channel within the coordinated TXOP.